The overall goal of this project is to develop novel vaccination approaches that not only enhance the magnitude but also enhance the functional quality of anti-HIV cellular and humoral immunity. Specifically, we propose to combine two new vaccination approaches developed recently at Emory University that showed great promise in rhesus macaques. The first approach uses CD40L, a co-stimulatory molecule for dendritic cells (DC) and B cells, expressed on the surface of HIV VLPs as a genetic adjuvant for enhancing the magnitude and functional quality of HIV-specific cellular and humoral immunity leading to enhanced protection from acquisition of SIV infection. Adjuvanting the DNA prime with CD40L of a DNA/MVA S1V239 vaccine significantly enhanced the functional quality of anti-SIV cellular and humoral immunity, and efficacy against a heterologous mucosal SlV challenge. The second approach uses a new MVA that lacks 4 immune modulatory genes (MVAA4) as a vaccine vector that showed a significant increase in the magnitude of HIV-specific cellular and humoral immunity in rhesus macaques. In this project, we combine these two new complementary approaches to develop a novel vaccination strategy against HIV. Project 2 has two specific aims: Aim 1 will test the relative immunogenicity and efficacy of MVA and MVAA4 boosts for enhancing protective antibody responses primed by the CD40L-adjuvanted DNA vaccine. Results from this Aim will direct the clinical use of MVAA4 as a boost for our DNA vaccines in a heterologous primeboost vaccination regimen against HIV. Aim 2 will test the safety, immunogenicity, and protective efficacy of MVA/CD40L.co-delivered with the MVA/HIV vaccine. Results from this Aim will direct the clinical use of MVA/CD40L as an adjuvant for a homologous prime-boost MVA vaccination regimen against HIV. These macaque studies will use HIV clade C immunogens and SHIV challenge. The Envs in the immunogen and the proposed challenge virus shares only 76% identity and thus will allow the opportunity to test protection against a heterologous tier-2 clade C Env.